mybin

commit 3134bfaf878aed2f16206a111d44bd820561c94e
parent c6ed0b4850f394d46a5d4bf9aa5cc0063a814d74
Author: Antoine Amarilli <a3nm@a3nm.net>
Date:   Sun,  4 Oct 2015 01:33:09 +0200

shrinkimg

Diffstat:
shrinkimg
 | 
80
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 80 insertions(+), 0 deletions(-)
diff --git a/shrinkimg b/shrinkimg
@@ -0,0 +1,80 @@
+#!/bin/bash
+
+# shrink the (possibly compressed) ext[2-4] disk image $1
+# and compress it to $2, overwriting it
+
+if [ "$#" -ne 2 ] || ! [ -f "$1" ]; then
+  echo "Usage: $0 INPUT.img(.xz|.gz|) OUTPUT.img.xz" >&2
+  exit 8
+fi
+
+FILE="$1"
+OUT="$2"
+DIR=$(dirname $(readlink -f "$OUT"))
+# create temporary file in directory of output
+TEMP=$(mktemp -p "$DIR")
+OSIZE=$(du -h "$FILE" | cut -f1)
+
+TYPE=$(file "$FILE" | cut -d ':' -f2)
+
+echo "creating $TEMP"
+
+case $TYPE in
+  *'XZ compressed'*)
+    pv -N "unxz" "$FILE" | xz -dc >$TEMP
+  ;;
+  *'gzip compressed'*)
+    pv -N "gunzip" "$FILE" | gzip -dc >$TEMP
+  ;;
+  *'ext'[2-4]' filesystem data'*)
+    pv -N "cp" "$FILE" >$TEMP
+  ;;
+  *)
+    echo "unknown type for $FILE: $TYPE"
+    echo "aborting"
+    exit 1
+  ;;
+esac
+
+TYPE2=$(file "$TEMP" | cut -d ':' -f2)
+
+case $TYPE2 in
+  *'ext'[2-4]' filesystem data'*)
+    # do nothing
+  ;;
+  *)
+    echo "unknown type after decompressing to $TEMP: $TYPE2"
+    echo "aborting WITHOUT removing $TEMP"
+    exit 1
+  ;;
+esac
+
+OSPACE=$(du -h "$TEMP" |cut -f1)
+
+chronic e2fsck -fn "$TEMP" || {
+  echo "e2fsck errors in $TEMP, please fix"
+  echo "aborting WITHOUT removing $TEMP"
+  exit 2
+}
+chronic resize2fs -M "$TEMP" || {
+  echo "error when resizing $TEMP";
+  echo "aborting WITHOUT removing $TEMP"
+  exit 3
+}
+
+NSPACE=$(du -h "$TEMP" |cut -f1)
+
+(pv -N "xz" "$TEMP" | xz -9c >"$OUT") || {
+  echo "error when compressing $TEMP, please fix";
+  echo "aborting WITHOUT removing $TEMP"
+  exit 4
+}
+rm $TEMP
+
+NSIZE=$(du -h "$OUT" | cut -f1)
+
+echo "successfully shrunk $FILE to $OUT"
+echo "uncompressed apparent size went from $OSPACE bytes to $NSPACE bytes"
+echo "compressed apparent size went from $OSIZE bytes to $NSIZE bytes"
+exit 0
+